Gaseous electrode segment type display device

ABSTRACT

This invention relates to display device. The display device comprises a sealed body comprising a base plate of an electrically insulating material, and at least one indication region formed on said base plate, a first metallic film superposed on the base plate and having an end portion extending outwardly of said sealed body, a first ceramic coat interposed between said electrically conducting metallic film in strip form and said first metallic film, at least one second metallic film representing a predetermined shape superposed on the base plate in such manner that predetermined portions of said first metallic film are disposed adjacent said second metallic film, and a second ceramic coat interposed between said first metallic film and said second metallic film in such a manner that said predetermined portions of said first metallic film are exposed.

United States Patent [1 1 Tsujimoto May 14, 1974 21 Appl. No.: 286,543

[30] Foreign Application Priority Data Sept. 11, 1971 Japan.....' 46-70072 Mar. 21, 1972 Japan 47-32362 May 16, 1972 Japan 47-56308 May 16, 1972 Japan 47-56309 [52] US. Cl 3l3/l09.5, 313/54, 313/217,

[51] int. Cl. HOlj 61/66 [58] Field of Search 313/1095, 221, 220, 225,

[56] References Cited UNITED STATES PATENTS 3,327,154 6/1967 Bowerman 3l3/lO9.5 3,588,571 6/1971 Uemura et a1. 313/1095 Primary Examiner-Palmer C. Demeo Attorney, Agent, or FirmStevens, Davis, Miller &

Mosher 57] ABSTRACT This invention relates to display device. The display device comprises a sealed body comprising a base plate of an electrically insulating material, and at least one indication region formed on said base plate, a first metallic film superposed on the base plate and having an end portion extending outwardly of said sealed body, a first ceramic coat interposed between said electrically conducting metallic film in strip form and said first metallic film, at least one second metallic film representing a predetermined shape superposed on the base plate in such manner that predetermined portions of said first metallic film are disposed adjacent said second metallic film, and a second ceramic coat interposed between said first metallic film and said second metallic film in such a manner that said predetermined portions of said first metallic film are exposed.

9 Claims,'l8 Drawing Figures PATENTEDMAY 14 I971. 3.81 1 O60 SHEET 3 BF 3 FIG. /3 l4 GASEOUS ELECTRODE SEGMENT TYPE DISPLAY DEVICE This invention relates to an display device for indicating letters, patterns, symbols or the like.

An object of this invention is to provide an display device of varying sizes having a very small thiclgness in which an. indication region has anarea of I to 256T) FIG. 4 shows a modification of the step shown in FIG.

FIG. 7 and FIG. 8 are an exploded perspective view and a transverse sectional view respectively of the display device;

FIG. 9 is an exploded perspective view ofa modification of the sealed body;

FIG. 10 is a schematic view in explanation of the second ceramic coat;

FIG. 11 is a plan view of the display device comprising a second embodiment of this invention;

FIG. 12 is a perspective view of the metallic plate of the display device of FIG. 11;

FIG. 13 and FIG. 14 are perspective views of modified forms of the metallic plate of FIG. 12;

FIG. 15 is a perspective view of another form of metallic plate used in the second embodiment of the display device according to this invention;

FIG. 16 is a plan view of the second embodiment of the display device according to this invention with certain parts being cut out;

FIG. 17 is a perspective view of another form of metallic plate used in the second embodiment of the display device according to this invention; and

FIG. 18 is a sectional view of the second embodiment of the display deviceaccording to this invention.

The invention will now be described with reference to embodiments shown in the drawings. According to one embodiment of this invention, a base plate 1 of electrically insulating material is formed with an air evacuation port 2 therein, and a plurality of electrically conducting metallic films 3a, 3b and 3c in strip form are attached to the upper surface of the base plate 1 as by vaporization deposition in vacuum, plating or other means depending on the type of material of the base plate 1 as shown in FIG. 1. A first ceramic coat 5 formed with openings 4a, 4b and 40 for exposing portions of the electrically conducting metallic strips 3a, 3b and 3c is applied to the upper surface of the base plate 1 to be disposed over the electrically conducting metallic strips, with end portions 3a, 3b, and 3c of the electrically conducting metallic strips being left uncovered by the ceramic coat 5 as shown in FIG. 2. In applying the first ceramic coat 5, a ceramic in powder form may be applied to the surface of the base plate 1 and melted in vacuum after being dried, or applied by means of a plasma spray in special cases.

Then, a first metallic film 6 in strip form serving as an electrode is applied to the upper surface of the first ceramic coat 5 to define a zone of the shape corresponding to that of a letter or other symbol to be indi cated, with an end portion 6' of the film 6 extending to one marginal portion of the base plate 1 as shown in FIG. 3. g

In place of forming the end portion 6 of the metallic film 6, an additional metallic film 3d in strip form may be applied to the base plate 1 when the electrically conducting metallic films 3a, 3b and 3c are applied to the base plate 1, and an opening 4d may be formed in addition to the openings 4a, 4b and 4c in the first ceramic coat 5 as shown in FIG. 4, so that connection can be made from the first metallic film 6 to the metallic film 3d through the additional opening 4d.

A second ceramic coat 7 is applied to the surface of the first metallic film 6 of the base plate assembly shown in FIG. 3, with the openings corresponding to the openings 4a, 4b and 4c and the zone of the predetermined shape defined by the coat 7 through which metallic film 6 is exposed to view without being covered by the second ceramic coat 7 as shown in FIG. 5. Second metallic films 8a, 8b and 8c in strip form arranged to indicate the predetermined shape to be indicated are applied as by vaporization deposition in vacuum to the upper surface of the second ceramic coat 7 in such manner that portions of the first metallic film 6 left uncovered by the second ceramic coat 7 are disposed adjacent the metallic films 8a, 8b and as shown in FIG. 6.

When applied as by vaporization deposition, the metallic films 8a, 8b and 8c are connected through the openings 4a, 4b and 4c to the electrically conducting metallic films 3a, 3b and 3c respectively.

Cover glass 9 formed with marginal portions bent at right angles to the surfaces of the cover glass and portions extending horizontally from the underside of the marginal portions as shown in FIG. 7 is placed on the base plate 1 in such a manner that the electrically conducting metallic film and portions 3a, 3b and 3c and the end portion 61 of the first metallic film 6 are left uncovered by the cover glass 9. When the cover glass 9 is placed on the base plate 1 and a pyroceram cement layer 10 between the base plate 1 and cover glass 9 is fused by heating to bond them integrally, they are closed and sealed airtight to provide a sealed body.

An air evacuation tube 11 is connected to the lower surface of the base plate 1 by a pyroceram cement layer 10' to maintain communication with the air evacuation opening 2 formed in the base plate 1. The air evacuation tube 11 is cut off by melting after a space 12 in the sealed body between the cover glass 9 and base plate 1 has been evacuated and filled with a rare gas and mercury. The pyroceram cement layers 10, 10 are such that the sealed body can be made sufficiently airtight. To this end, the marginal portions of the base plate I extend outwardly to form offset portions between the base plate 1 and cover glass 9, and the air evacuation tube 11 is formed at its base with a major diameter portion 11 so that a recess is formed between the tube 11 and the base plate. Thus, a sufficiently large amount of cement can be accumulated in the offset portions and the recess to enable the sealed body to be perfectly airtight.

In one aspect of the invention, the display device according to this invention is constructed as aforementioned. The predetermined portions of the first metallic film 6 are disposed adjacent the second metallic films 8a, 8b and 8c. With this arrangement, if a voltage is applied by using the end portion 6' of the first metallic film 6 as an anodeand any of the end portions 3a, 3b or 3c of the electrically conducting metallic films as a cathode, the letter or symbol represented by the second metallic films will be indicated by cathode glow discharge. In the illustrated example, the symbol can be indicated by all the second metallic films 8a, 8b and 8c and the symbol can be indicated by the second metallic film 8b alone.

As can be seen from the foregoing description, it is possible to indicate a symbol or letter of any shape as desired by varying the arrangement of the second metallic films 8a, 8b and 80. When it is required to increase the number of the second metallic films, the number of electrically conducting metallic films in strip form 3a, 3b, 3c is also increased so that the corresponding electrically conducting metallic. films may be connected to the second metallic films. Discharge can be effected satisfactorily even if the first metallic film 6 and the second metallic films 8a, 8b, 8c are not disposed in the same plane.

The first and second ceramic coats and 7 are intended to prevent short-circuiting between the anode and the cathode and electric connection between the various indication portions. They may be provided at least in intersections between the metallic films which need to be insulated.

The display device according to this invention has an overall thickness in a range of from 0.2 to 0.3 millimeter even if all the metallic films and ceramic coats are superposed one over another, and the marginal portions of the cover glass 9 have only to have a height of l millimeter. Thus, the overall maximum thickness of the indication device will be 3 millimeters at most even if the base plate 1 and cover glass 9 have a thickness of l millimeter. I

In thepresent invention, the cover glass 9 for producing a sealed member may be in two pieces and comprises a planar glass member 9a and a frame-shaped spacer 9b as shown in FIG. 9. The planar glass member 9a and frame-shaped spacer 9b are bonded with a cement to the base plate 1, so that the base plate 1, planar glass member 9a and frame-shaped spacer 9b are preferably made of the same material. However, the base plate 1 may be made of alumina ceramic, the planar glass member 9a soda glass or lead glass, and the frameshaped spacer 9b steatite (MgO'SiO If the base plate 1 is made as a two-layer structure and comprises an alumina layer and a steatite layer with the alumina layer serving as an upper surface, printing of the metallic films on the upper surface ofthe base layer will be facilitated and the connecting of the air evacuation tube of glass to the lower surface can be facilitated.

As aforementioned, it is required to expose the openings 4a, 4b and 40 when the second ceramic coat 7 is formed without closing them by the coat. To attain the end, the second ceramic coat 7 may be formed therein with openings 4a, 4b and 4c sufficiently larger than the openings 4a, 4b and 4c so that the openings 4a, 4b and 4c may be indexed with the openings 40, 4b and 40 as shown in FIG. 10.

The air evacuation tube 11 need not be made of glass. A metallic tube, such for example as a copper tube, nickel tube or the like, capable of being pinchsealed, which is used generally in a discharge tube, may be utilized as the air evacuation tube 11. When this type of air evacuation tube is used, it can be positively connected to the base plate if the base plate is made as a two-layer structure as aforementioned.

By adding a radioactive substance, such for example as cobalt 60, krypton or promethium 147, to the rare gas and mercury filled in the sealed body, it is possible readily to cause glow discharge to occur and to render the glow discharge produced to be stabilized at all times.

FIG. 11 shows a second embodiment of the display device according to this invention in which there are two indication regions A and B in a sealed body. The device of this type offers the advantages of enabling to obtain a compact overall size and a small thickness in an display device and to use an outer circuit of simple When the number to be indicated during the course of an addition operation changes from (9) to 10) or one symbol to be indicated changes to another symbol in the order of several hundred microseconds to several scores of microseconds, leap discharge may occur between the cathodes 8a, of the first indication region A and the anode 6 of the second indication region B or conversely between the anode 6 of the first indication region A and the cathodes 8a, of the second indication region B.

This defect derives from the facts that the two indication regions A and B are disposed close to each other to obtain a compact overall size in an display device, that the anode and the cathodes are disposed in the same plane, and that the symbols to be indicated are changed rapidly from one to another. The defect can, therefore, be eliminated by increasing the spacing between the two indication regions, avoiding the arrangement in which the anode and cathodes are disposed in the same plane, and delaying the change in symbols indicated. However, these measures will do more harm than good because, if any of them is taken, the inherent advantages of the display device of the type described will be reduced.

This defect can be obviated by using, for example, a metallic plate 13 of 0.6 millimeter in thickness, for example, shown in FIG. 12. The metallic plate 13 is formed therein with two windows l4'of the same size and position as the indication regions A and B, and placed on the insulating base-plate 1 in such manner that the windows 14 define the indication regions A and B and the space in the sealed body produced in this way has a thickness of 1.0 millimeter. By this arrangement, it is possible to preclude leap discharge between the first indication region A and the second indication region B even if the space between the two regions is reduced and the symbol indicated is changed rapidly from one to another.

This is accounted for by the facts that the portion of the metallic plate 13 which is disposed between the two indication regions offers obstacle to leap discharge between the two regions, and that when a voltage is applied between the cathode or cathodes and the anode of each of the two regions A and B, the discharge space and the insulator serve as one component of a capacitor and the metallic plate I3 is charged to havea potential intermediate between the potential of the cathode and the potential of the anode, thereby preventing leap discharge of electrons. The metallic plate 13 may be maintained at a predetermined potential in order to ensure that leap discharge is prevented by the metallic plate 13.

In order to preclude leap discharge, it is necessary that the metallic plate 13 has a thickness t which can be expressed by the formula t/T 0.3 where T is the distance between the cover glass and base plate. When the metallic plate 13 has a small thickness, however, the metallic plate can be worked on as shown in FIG. 13 and FIG. 14 to provide an obstacle wall or walls 15. If this is the case, the wall 15 has only to have a height I which can be expressed by the formula t/T 2 0.3 as

, is the case with the thickness tof the metallic plate. The

metallic plate 13 may be formed by coating an insulator with a conductor layer.

To preclude leap discharge, an independent conductor wall may be provided between the adjacent indication regions. However, since to 16 indication regions or at least six indication regions should be provided for practical purposes, the provision of a conductor wall between the adjacent indication regions is not desirable because it involves a time-consuming operation and stands in the way of assembling the parts accurately.

FIG. shows a modification of the metallic plate used in the second embodiment of this invention. As shown, the metallic plate 13 is formed on its lower surface with positioning tongues 1311 depending downwardly therefrom at right angles thereto, and placed on the insulating base plate 1 formed with recesses 10 in positions corresponding to the positioning tongues 13a as shown in FIG. 16. By inserting the positioning tongues 13a in the respective recesses la, it is possible to accurately position the metallic plate 13 on the base plate 1 and secure the former to the latter. When this form of metallic plate is used, displacement of the metallic plate 13 with respect to the base plate 1 can be prevented, and the metallic plate 13 can perform its function satisfactorily.

FIG. 17 shows still another form of the metallic plate used in the second embodiment of. this invention. As shown, the metallic plate 13 is formed with a positioning tongue 13b extending outwardly from the lower surface of the metallic plate I3 parallel to its lower surface. The forward end portion of the positioning tongue 13]) is inserted between the portions of the cover glass 9 and insulating base plate 1 which are to be bonded together, and the insulating base plate I, tongue 13b and cover glass 9 are bonded to one another integrally by using an adhesive agent 16 having a coefficient of expansion equal or approximate to the coefficient of expansion of the tongue 131;, as shown in FIG. 18.

Preferably, the coefficient of expansion of the adhesive agent 16 is equal to that of the tongue 1312. To this end, a pyroceram cement (coefficient of expansion, 6 X l0 /deg) can be used as the adhesive agent and kovar (coefficient of expansion, 8 X lO /deg) can be used as a material for the tongue 13b.

In the bonding operation, the molten adhesive agent may be brought into contact with the metallic plate and the solidified adhesive agent 16 may be cracked due to the thermal expansion of the metallic plate 13 caused by the heat treatment to which the metallic plate is subsequently subjected or the heat produced by discharge while the indication device is in service. This defect can be eliminated by providing a spacing t, of over 0.5 millimeter between the inner sides of the cover glass 9 and the edges of the metallic plate 13.

What is claimed is:

l. A segment type display device comprising a sealed body comprising a base plate of an electrically insulating material, a cover glass and a tip of an air evacuation tube, a plurality of indication regions formed on said base plate, a discharge precluding electrically conducting body for separating said plurality of indication regions from one another, a gas for discharging filled in said sealed body, offset portions formed between said base plate and the marginal portions of said cover glass, a recess formed between said base plate and a major diameter portion of said air evacuation tube, and pyloceram cements accumulated in said offset portions and recess for airtight seal of said sealed body, each of said indication regions comprising at least one electrically conducting metallic film in strip form superposed on the upper surface of the base plate and having an end portion extending outwardly of said sealed body, a first metallic film superposed on the base plate and having an end portion extending outwardly of said sealed body, a first ceramic coat interposed between said electrically conducting metallic film in strip form and said first metallic film, at least one second metallic film representing a predetermined shape superposed on the base plate in such manner that predetermined portions of said first metallic film are disposed adjacent said second metallic film, said second metallic film being connected to corresponding said electricallyconducting metallic film in strip form, and a second ceramic coat interposed between said first metallic film and said second metallic film in such a manner that said predetermined portions of said first metallic film are exposed, whereby cathode glow discharge can be produced between said predetermined portions of said first metallic film and said second metallic film, and said discharge precluding electrically conducting body comprising a metallic plate having therein a plurality of windows of the same size and position as said indication regions and placed on said base plate.

2. A segment type display device comprising a sealed body comprising a base plate of an electrically insulating material, a cover glass, a tip of an air evacuation tube connected to the lower surface of the base plate, and pyroceram cement layers integrally bonding the aforementioned elements, said sealed body having rare gas and mercury filled therein and being sealed air tight; and at least one indication region formed on said base plate; said indication region comprising at least one electrically conducting metallic film in strip form superposed on the upper surface of the base plate and having an end portion extending outwardly of said sealed body, a first metallic film superposed on the base plate and having an end portion extending outwardly of said sealed body, a first ceramic coat interposed between said electrically conducting metallic film in strip form and said first metallic film, at lease one second metallic film representing a predetermined shape superposed on the base plate in such manner that predetermined portions of said first metallic film are disposed adjacent said second metallic film, said second metallic film being connected to corresponding said electrically conducting metallic film in strip form, and a second ceramic coat interposed between said first metallic film and second metallic film in such a manner tha said predetermined portions of said first metallic film are exposed, whereby cathode glow discharge can be produced between said predetermined portions of said first metallic film and said second metallic film.

3. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body has a plurality of indication regions thereon, and there is provided a discharge precluding electrically conducting body for segregating said plurality of indication regions from one another.

4. A segment type display device as set forth in claim 2 wherein said base plate has a plurality of indication regions thereon, and there are provided a discharge precluding conductor for segregating said plurality of indication regions from one another, at least one recess formed in said base plate, and at least one positioning tongue projecting from said discharge precluding conductor and adapted to be received in said recess in said base plate.

5. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body has a plurality of indication regions thereon, and there are provided a discharge precluding conductor for segregating said plurality of indication regions from one another, and at least one positioning tongue projecting outwardly from said discharge precluding conductor and adapted to be bonded by an adhesive agent to said base plate.

6. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body is made of alumina, and said sealed body further comprises a frame-shaped spacer made of steatite.

7. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body is made of alumina, and said sealed body further comprises a frame-shaped spacer made ,of steatite, and said tip of an air evacuation tube is made of metal.

8. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body is a twolayer structure having an upper layer made of alumina and a lower layer made of steatite, and said sealed body further comprises a frame-shaped spacer made of steatite.

9. A segment type display device comprising a sealed body comprising a base plate of an electrically insulating material, a cover glass, a tip of an air evacuation tube connected to the lower surface of the base plate, and pyroceram cement layers integrally bonding the aforementioned elements, said sealed body having rare gas and mercury as well as a radioactive substance filled therein and being sealed airtight; and at least one indication region formed on said base plate; said indi cation region comprising at least one electrically conducting metallic film in strip form superposed on the upper surface of the base plate and having an end portion extending outwardly of said sealed body, a first metallic film superposed on the base plate and having an end portion extending outwardly of said sealed body, a first ceramic coat interposed between said electrically conducting metallic film in strip form and said first metallic film, at least one second metallic film representing a predetermined shape superposed on the base plate in such manner that predetermined portions of said first metallic film are disposed adjacent said second metallic film, said second metallic film being connected to corresponding said electrically conducting metallic film in strip form, and a second ceramic coat interposed between said first metallic film and said second metallic film in such a manner that said predetermined portions of said first metallic film are exposed, whereby cathode glow discharge can be produced between said predetermined portions of said first metallic 

2. A segment type display device comprising a sealed body comprising a base plate of an electrically insulating material, a cover glass, a tip of an air evacuation tube connected to the lower surface of the base plate, and pyroceram cement layers integrally bonding the aforementioned elements, said sealed body having rare gas and mercury filled therein and being sealed air tight; and at least one indication region formed on said base plate; said indication region comprising at least one electrically conducting metallic film in strip form superposed on the upper surface of the base plate and having an end portion extending outwardly of said sealed body, a first metallic film superposed on the base plate and having an end portion extending outwardly of said sealed body, a first ceramic coat interposed between said electrically conducting metallic film in strip form and said first metallic film, at lease one second metallic film representing a predetermined shape superposed on the base plate in such manner that predetermined portions of said first metallic film are disposed adjacent said second metallic film, said second metallic film being connected to corresponding said electrically conducting metallic film in strip form, and a second ceramic coat interposed between said first metallic film and second metallic film in such a manner tha said predetermined portions of said first metallic film are exposed, whereby cathode glow discharge can be produced between said predetermined portions of said first metallic film and said second metallic film.
 3. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body has a plurality of indication regions thereon, and there is provided a discharge precluding electrically conducting body for segregating said plurality of indication regions from one another.
 4. A segment type display device as set forth in claim 2 wherein said base plate has a plurality of indication regions thereon, and there are provided a discharge precluding conductor for segregating said plurality of indication regions from one another, at least one recess formed in said base plate, and at least one positioning tongue projecting from said discharge precluding conductor and Adapted to be received in said recess in said base plate.
 5. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body has a plurality of indication regions thereon, and there are provided a discharge precluding conductor for segregating said plurality of indication regions from one another, and at least one positioning tongue projecting outwardly from said discharge precluding conductor and adapted to be bonded by an adhesive agent to said base plate.
 6. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body is made of alumina, and said sealed body further comprises a frame-shaped spacer made of steatite.
 7. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body is made of alumina, and said sealed body further comprises a frame-shaped spacer made of steatite, and said tip of an air evacuation tube is made of metal.
 8. A segment type display device as set forth in claim 2 wherein said base plate of said sealed body is a two-layer structure having an upper layer made of alumina and a lower layer made of steatite, and said sealed body further comprises a frame-shaped spacer made of steatite.
 9. A segment type display device comprising a sealed body comprising a base plate of an electrically insulating material, a cover glass, a tip of an air evacuation tube connected to the lower surface of the base plate, and pyroceram cement layers integrally bonding the aforementioned elements, said sealed body having rare gas and mercury as well as a radioactive substance filled therein and being sealed airtight; and at least one indication region formed on said base plate; said indication region comprising at least one electrically conducting metallic film in strip form superposed on the upper surface of the base plate and having an end portion extending outwardly of said sealed body, a first metallic film superposed on the base plate and having an end portion extending outwardly of said sealed body, a first ceramic coat interposed between said electrically conducting metallic film in strip form and said first metallic film, at least one second metallic film representing a predetermined shape superposed on the base plate in such manner that predetermined portions of said first metallic film are disposed adjacent said second metallic film, said second metallic film being connected to corresponding said electrically conducting metallic film in strip form, and a second ceramic coat interposed between said first metallic film and said second metallic film in such a manner that said predetermined portions of said first metallic film are exposed, whereby cathode glow discharge can be produced between said predetermined portions of said first metallic film and said second metallic film. 